Hot water repairs: diagnose before you replace
Hot water repairs cover faults that stop a system heating, cause leaks, or make it unsafe, without replacing the whole unit. Hot Water System Sydney arranges independent local licensed plumbers across Sydney to diagnose hot water problems and quote on the fix. If the fault cannot be economically repaired, the plumber should say so and price a replacement.
First checks you can do safely
Before calling, a few checks can save time:
- Electric: is the hot water circuit breaker on at the switchboard? If it has tripped and trips again when reset, leave it off.
- Off-peak electric: has the tank simply run out before its next heating period?
- Gas storage: is the pilot lit? Follow the relighting instructions on the unit's label if you are comfortable doing so.
- Gas continuous flow: is the unit powered, and is there an error code on the controller? Note it down.
- Everything: is gas on at the meter, and is the cold water isolation valve open?
If you smell gas, turn it off at the meter, do not use switches or flames, ventilate, and call a licensed gasfitter or the gas network's emergency line.
Common faults and what they usually mean
Gas storage tanks
- Pilot will not stay lit: often a thermocouple or gas control valve fault.
- Burner lights then goes out: flue or air supply problems, or a control fault.
- Water hot but not enough of it: dip tube, sediment, burner condition or undersizing.
Gas continuous flow
- No ignition or error codes: igniter, flame sensor, fan, or flow sensor faults; the code narrows it down.
- Temperature swings: low flow at the tap, scale in the heat exchanger, or a gas supply too small for the unit.
Electric storage
- No hot water: element, thermostat or over-temperature cut-out.
- Breaker trips: often a failed element shorting to earth.
- Lukewarm water: a failed element in two-element tanks, or a thermostat fault.
Heat pumps
- Not heating: fan or compressor faults, sensor faults, or refrigerant problems.
- Unusually loud: fan obstruction, bearing wear or mounting issues.
All storage systems
- Water around the base: a fitting, valve or the tank itself. A leaking inner tank cannot be repaired.
- Relief valve running constantly: faulty valve, high mains pressure, or a thermostat fault.
- Rusty hot water: corrosion inside the tank, often a sign the anode is spent.
Repair or replace?
The plumber should weigh the fault against the unit's age and condition. A new thermocouple on a gas tank in good condition is usually a sensible repair. A second element on an old tank that is showing signs of corrosion is less convincing. A leaking tank means replacement. If you are unsure, ask for both options in writing; see hot water system replacement.
Warranty
If your system is relatively new, check the manufacturer's warranty before paying anyone. Have the model and serial number, installation date and proof of purchase ready. The manufacturer may send its own service agent.
Licensing
Repairs to gas components are gasfitting work, water-side work is plumbing work, and electrical repairs need a licensed electrician. We ask the contractors we work with to hold the licences and insurance the job needs — ask to see them before work starts.
Prices
Repair price ranges are on the hot water system cost guide. For what to do the moment your system fails, read the day your hot water fails.